Emergency workers evacuate people from a damaged nursing home after the explosion at the fertilizer plant in West, Tex., on April 17, 2013. (Rod Aydelotte/AP)

Sometime before 7:30 p.m. on April 17, 2013, in the small town of West, Tex., a fire broke out at the West Fertilizer Company plant.

Thirty volunteers made up the town’s fire department. They heard the beep on their pagers, said goodbye to their families and headed to the source of the menacing black smoke.

Some of them, 12 of them, wouldn’t come back.

Twenty minutes after the fire started, the plant exploded — so powerfully that it registered as a 2.1-magnitude earthquake on the Richter scale. A total of 15 people died in the blast, including the 12 volunteer first responders. Two hundred sixty people were injured, and 150 buildings in the vicinity were damaged. Half of them, including two schools, had to be demolished.

Arson caused the fire, federal investigators concluded three years later. But 80,000 to 100,000 pounds of unsafely stored fertilizer-grade ammonium nitrate was the source of the disastrous explosion.

The fatal blast prompted the Environmental Protection Agency to make serious changes to regulations about how companies store dangerous flammable chemicals and how they develop risk-management plans. The new rules were set to take effect in June 2017, but they were held up by EPA Administrator Scott Pruitt after he took office.

Now Pruitt wants to rescind most of the safety regulations, saying that a lot of them imposed “unnecessary regulatory burdens” on the chemical industry. Pruitt’s proposed changes, signed Thursday, are subject to public comment.

“Accident prevention is a top priority at EPA, and this proposed rule will ensure proper emergency planning and continue the trend of fewer significant accidents involving chemicals,” Pruitt said in a statement. “The rule proposes to reduce unnecessary regulatory burdens, address the concerns of stakeholders and emergency responders on the ground, and save Americans roughly $88 million a year.”

The bulk of the claimed savings would come from getting rid of a rule requiring owners of a chemical plant to evaluate options for safer technology and procedures that would mitigate hazards, according to an EPA report. He also seeks to rescind rules requiring companies to conduct a “root-cause analysis” after a “catastrophic” chemical release or an incident that might have caused one and to perform a third-party compliance audit after an accident at a plant or when conditions are discovered that could lead to an accidental release of chemicals.

Pruitt’s move to dismantle these regulations is part of a broader push to scrap Obama-era environmental rules, a strategy that has drawn intense criticism from environmental groups. On Thursday, some accused Pruitt of bending to the chemical industry’s will.

“EPA administrators are supposed to push for safeguards to protect workers and residents from deadly catastrophes, like the one we saw in 2013 when the West, Tex., fertilizer plant explosion killed 15 people,” said Environmental Working Group President Ken Cook in a statement. “But this is Scott Pruitt. There apparently is no favor he won’t do for the chemical industry. Repealing safety measures at industry’s behest is just all in a day’s work.”

Pruitt also would eliminate a requirement that chemical plants release information to the public about the types of chemicals stored, the types of procedures the plant has in place to mitigate the risks and, crucially, what to do in case of an emergency. He is not seeking to rescind the portion of the rule that made this information more readily available to first responders.

That Obama administration’s rule was proposed after an investigation by the U.S. Chemical Safety and Hazard Investigation Board, which called the explosion “one of the most destructive incidents ever investigated.” The board stressed the need for changes in both regulations and transparency to prevent a repeat tragedy.

“CSB’s analysis shows that the risk to the public from a catastrophic incident exists at least within the state of Texas, if not more broadly,” the agency wrote. “For example, 19 other Texas facilities storing more than 10,000 pounds of fertilizer-grade ammonium nitrate are located within 0.5 miles of a school, hospital, or nursing home, raising concerns that an incident with offsite consequences of this magnitude could happen again.”

In addition to identifying safety-inspection failures and other lax regulations, the CSB report found that few people in West appeared aware of the explosive nature of the fertilizer-grade ammonium nitrate inside the West Fertilizer Co. Some of the plant’s own workers were not aware of the chemical compound’s hazards, the report said. The volunteer firefighters had no plan in place to combat a hazardous-materials incident at the plant, it said. And instead of evacuating immediately, residents watched the fire from parking lots and front yards, exposing them to the blast and flying debris.

But Pruitt argued that making the information about the risks of the chemicals and the company’s emergency response plans available to the public exposed the plants to terrorists, a position he took before he became President Trump’s EPA administrator.

“The safety of these manufacturing, processing and storage facilities should be a priority for us all,” Pruitt wrote in a July 2016 letter to then-EPA Administrator Gina McCarthy while he was the attorney general of Oklahoma, “but safety encompasses more than preventing accidental releases of chemicals, it also encompasses preventing intentional releases caused by bad actors seeking to harm our citizens.”

On Thursday, the chemical industry cheered Pruitt’s decision to toss out the Obama-era regulations during a signing ceremony.

“The EPA’s Risk Management Plan Rule as proposed under the Obama Administration would have imposed significant new costs on the industry without identifying or quantifying the safety benefits to be achieved through the new requirements,” Eric Byer, president of the National Association of Chemical Distributors, said in a statement.